<?php
/**
 * Xcache storage engine for cache.
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @package       Cake.Cache.Engine
 * @since         CakePHP(tm) v 1.2.0.4947
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */

/**
 * Xcache storage engine for cache
 *
 * @link          http://trac.lighttpd.net/xcache/ Xcache
 * @package       Cake.Cache.Engine
 */
class XcacheEngine extends CacheEngine {

	/**
	 * Settings
	 *
	 *  - PHP_AUTH_USER = xcache.admin.user, default cake
	 *  - PHP_AUTH_PW = xcache.admin.password, default cake
	 *
	 * @var array
	 */
	public $settings = array();

	/**
	 * Initialize the Cache Engine
	 *
	 * Called automatically by the cache frontend
	 * To reinitialize the settings call Cache::engine('EngineName', [optional] settings = array());
	 *
	 * @param array $settings array of setting for the engine
	 *
	 * @return bool True if the engine has been successfully initialized, false if not
	 */
	public function init($settings = array()) {
		if (php_sapi_name() !== 'cli') {
			parent::init(array_merge(array(
					'engine' => 'Xcache',
					'prefix' => Inflector::slug(APP_DIR) . '_',
					'PHP_AUTH_USER' => 'user',
					'PHP_AUTH_PW' => 'password'
				), $settings)
			);
			return function_exists('xcache_info');
		}
		return false;
	}

	/**
	 * Write data for key into cache
	 *
	 * @param string $key Identifier for the data
	 * @param mixed  $value Data to be cached
	 * @param int    $duration How long to cache the data, in seconds
	 *
	 * @return bool True if the data was successfully cached, false on failure
	 */
	public function write($key, $value, $duration) {
		$expires = time() + $duration;
		xcache_set($key . '_expires', $expires, $duration);
		return xcache_set($key, $value, $duration);
	}

	/**
	 * Read a key from the cache
	 *
	 * @param string $key Identifier for the data
	 *
	 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error
	 *     fetching it
	 */
	public function read($key) {
		if (xcache_isset($key)) {
			$time = time();
			$cachetime = (int) xcache_get($key . '_expires');
			if ($cachetime < $time || ($time + $this->settings['duration']) < $cachetime) {
				return false;
			}
			return xcache_get($key);
		}
		return false;
	}

	/**
	 * Increments the value of an integer cached key
	 * If the cache key is not an integer it will be treated as 0
	 *
	 * @param string $key Identifier for the data
	 * @param int    $offset How much to increment
	 *
	 * @return New incremented value, false otherwise
	 */
	public function increment($key, $offset = 1) {
		return xcache_inc($key, $offset);
	}

	/**
	 * Decrements the value of an integer cached key.
	 * If the cache key is not an integer it will be treated as 0
	 *
	 * @param string $key Identifier for the data
	 * @param int    $offset How much to subtract
	 *
	 * @return New decremented value, false otherwise
	 */
	public function decrement($key, $offset = 1) {
		return xcache_dec($key, $offset);
	}

	/**
	 * Delete a key from the cache
	 *
	 * @param string $key Identifier for the data
	 *
	 * @return bool True if the value was successfully deleted, false if it didn't exist or couldn't be removed
	 */
	public function delete($key) {
		return xcache_unset($key);
	}

	/**
	 * Delete all keys from the cache
	 *
	 * @param bool $check If true no deletes will occur and instead CakePHP will rely
	 *   on key TTL values.
	 *
	 * @return bool True if the cache was successfully cleared, false otherwise
	 */
	public function clear($check) {
		$this->_auth();
		$max = xcache_count(XC_TYPE_VAR);
		for ($i = 0; $i < $max; $i++) {
			xcache_clear_cache(XC_TYPE_VAR, $i);
		}
		$this->_auth(true);
		return true;
	}

	/**
	 * Returns the `group value` for each of the configured groups
	 * If the group initial value was not found, then it initializes
	 * the group accordingly.
	 *
	 * @return array
	 */
	public function groups() {
		$result = array();
		foreach ($this->settings['groups'] as $group) {
			$value = xcache_get($this->settings['prefix'] . $group);
			if (!$value) {
				$value = 1;
				xcache_set($this->settings['prefix'] . $group, $value, 0);
			}
			$result[] = $group . $value;
		}
		return $result;
	}

	/**
	 * Increments the group value to simulate deletion of all keys under a group
	 * old values will remain in storage until they expire.
	 *
	 * @param string $group The group to clear.
	 *
	 * @return bool success
	 */
	public function clearGroup($group) {
		return (bool) xcache_inc($this->settings['prefix'] . $group, 1);
	}

	/**
	 * Populates and reverses $_SERVER authentication values
	 * Makes necessary changes (and reverting them back) in $_SERVER
	 *
	 * This has to be done because xcache_clear_cache() needs to pass Basic Http Auth
	 * (see xcache.admin configuration settings)
	 *
	 * @param bool $reverse Revert changes
	 *
	 * @return void
	 */
	protected function _auth($reverse = false) {
		static $backup = array();
		$keys = array('PHP_AUTH_USER' => 'user', 'PHP_AUTH_PW' => 'password');
		foreach ($keys as $key => $setting) {
			if ($reverse) {
				if (isset($backup[$key])) {
					$_SERVER[$key] = $backup[$key];
					unset($backup[$key]);
				} else {
					unset($_SERVER[$key]);
				}
			} else {
				$value = env($key);
				if (!empty($value)) {
					$backup[$key] = $value;
				}
				if (!empty($this->settings[$setting])) {
					$_SERVER[$key] = $this->settings[$setting];
				} elseif (!empty($this->settings[$key])) {
					$_SERVER[$key] = $this->settings[$key];
				} else {
					$_SERVER[$key] = $value;
				}
			}
		}
	}
}
